BQ24103: VBAT monitoring question

Juan Jose Frutos Andreu

Part Number: BQ24103
Other Parts Discussed in Thread: BQ24130

Hi,

We are designing a 1cell Li-ion custom battery pack.

The issue is that in order to fulfill one certification the design must pass, the battery pack shall have a set of diodes in the charge path connector and the Voltage Bat monitoring shall be current limited using a 10K resistor.

The custom battery pack simplified architecture is shown in this figure:

We have choosen the BQ241Xx IC for the charger design, due to the Bat voltage monitoring and charge is made via different pins. So the charger connector will be tied to the BAT pin and OUT pin of the BQ241xx.

Will we have any problem due to the 10K resistor or the diode stage?

Best Regards,

Juanjo

over 6 years ago

0 ezhao over 6 years ago

TI__Genius 10240 points

Juan,

The configuration has some issue as the differential voltage between SNS and BAT representing the charging current. There is a extra diode between SNS and BAT for the configuration. How much are the charging current and voltage?

0 Juan Jose Frutos Andreu over 6 years ago in reply to ezhao

Intellectual 610 points

Hi Ezhao,

In order to fulfill the required certification, the battery pack must be assemblied with at least three discrete diodes, no matter the protections implemented in the IC.

The charguing current can be set as low as possible, we would like to charge it at least at 750mA, but it can be lower if simplifies the design. We are designing the system for a 1S1P Li-ion cell, so the final voltage must be set to 4,2V. The voltage drop accross the diode stage will be lower than 2,4V (0,8Vmax/diode).

Will the charger work properly with this requirements?

Best Regards,

Juanjo

0 ezhao over 6 years ago in reply to Juan Jose Frutos Andreu

TI__Genius 10240 points

Juanjo,

I think you need battery voltage remote sensing. Please check whether BQ24130 can meet your requirement. The BAT pin senses the battery voltage instead of the SRN.

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BQ24103: VBAT monitoring question